Yesterday a seminar was held at the UCL Constitution Unit to mark the launch of a book on the issue by Bob Morris. Church and State in 21st Century Britain is a meticulous analysis of the situation. No such study can be entirely neutral, but Morris seems to have no religious agenda; his aim is to point out that establishment is at odds with the principle of religious equality, making it “anomalous to the point of unsustainability”. He is wary of the term “disestablishment” but he does advocate the big reform – ending the monarch’s need to be Anglican.

In his presentation yesterday he said that reform would ideally come from the church itself. Otherwise it is likely to have reform thrust upon it, in a way it cannot control. So it is in its interest to lead the process. He acknowledged that here is little sign of this willingness as yet, but seemed hopeful that a fresh look at the issue might change that.

In the discussion that followed three Anglican representatives spoke. Each offered a slightly different flavour of the old conservative line: that it would be perilous to mess with our ancient constitution, that it might unleash an aggressive secularism. None admitted that there was a problem here that had to be faced.

These speakers confirmed my view that the Church of England looks very nice and liberal from a slight distance but at heart its philosophy is high Tory: tradition is sacred, those who want to tamper with it are dangerously shallow. I know of almost no Anglican who has said anything different, who admits Morris’ basic point that reform is necessary, so that we can have a constitution we can really affirm, and participate in, rather than an alienating relic from the imperial past. One exception is the Oxford theologian George Pattison, who has recently called for a more honest debate within the church (in an article in The Church Times). It is worth noting that Rowan Williams has failed to start the debate; he has allowed the reactionary position to become stronger – a piece of major political cowardice.

Might reform come from elsewhere? Of course the secularist lobbies advocate it, but in a sense this is unhelpful: it makes it seem an atheist cause, and so strenghtens the hand of the Anglicans, who scarify with the prospect of a Dawkinsish tyranny. Ideally it would come from a political movement that was also Christian, led by a new Cromwell figure.

Why is disestablishment not a mainstream liberal cause? It baffles me frankly. Why is it hardly ever mentioned by the columnists of this paper, except as a quick aside? To my mind it is the very essence of liberalism, that church and state should be separate. This is the English revolution that we have never quite had. It is the way to a new sort of political participation, a new sense that we are citizens of a modern state. Other aspects of constitutional change, and other liberal causes such as CCTV, DNA database and ID Cards are pathetically small-fry compared to this.

Perhaps we should not be surprised that the Prince of Wales, ­working “prince to prince”, has persuaded the Qatar royal family to reject Richard ­Rogers’s ­design for the new ­housing project on the site of the Chelsea Barracks. As Rogers says, architecture “evolves and moves forward”. The Prince of Wales does not. For all his pretensions, he personifies a mindless admiration for antiquity. He thinks of Britain as a theme park where gawping tourists and sycophantic “subjects” can briefly relive the past. The monarchy is, of course, the central exhibit – described by its more sophisticated adherents as decorative, convenient and harmless. It ceases to be any of those things when it imposes its prejudices on the public.

Prince Charles is clearly a ­philistine – a quality which would not be a ­handicap in his line of work were it not for the presumption that prompts him to believe he is an expert on subjects about which he is ignorant. He knows nothing about architecture, as Poundbury proves. It is not surprising that Clarence House primly announces: “We don’t want to get into a debate with Richard Rogers.” That pathetic admission is a perfect example of the prince wanting to have his organic cake and eat it. He is prepared to step outside the bounds of royal propriety to interfere in the life of the country, but when asked to defend his intrusion he becomes again the heir to the throne who must avoid controversy.

Richard Rogers, in an admirably ­moderate response to the Chelsea outrage, takes pity on the prince – “an unemployed individual looking for a job”. It is fair to say in the royal defence that the long wait debilitated all his predecessors. But that does not excuse behaviour that should alarm convinced monarchists and add thousands of recruits to the republican cause. His interference in the Chelsea ­Barracks decision exemplifies all that is most unacceptable about a hereditary monarchy. As a result of blood and birth, a middle-aged man of no particular merit enjoys a special status in society. More sensible members of the royal family are discreet about their “divine right”. Charles recklessly chooses to use his position to advocate his favourite causes – alternative medicine, badger culling, architectural pastiche.

The result, in our still deferential ­society, is the propagation of weird ideas. I recall a past president of the Royal Institute of British Architects rhetorically asking me to estimate how many new council offices would, thanks to the Prince of Wales, have polystyrene Corinthian pillars in their public rooms. But in modern Britain, the next head of state should be more than a bad and highly expensive joke. The one good thing to come out of the whole Chelsea Barracks scandal is the attention that it focuses on the anachronism which is the hereditary monarchy and the ­consequences of a royal family. No one can imagine an elected head of state interfering ­capriciously and arbitrarily in a quasi-judicial planning decision. The idea that his or her offspring might claim a special right to influence the character of a major building development is absurd. Therein lies the truth about the monarchy. A “royal family” – superior because of its genes – is an absurdity.

Perhaps, as long as the royal family plays within the rules, that only matters to egalitarians who hate the idea of a hierarchical society in which the Windsors are the publicly acknowledged pinnacle. In this tight little right little island it is difficult to stimulate much opposition to a hereditary monarchy as long as it accepts that its function is to be polite to foreign heads of state, present the FA Cup to the winner and make platitudinous speeches to mark solemn occasions. But once the sovereign and her family begin to believe that they have an intrinsic importance and a duty to propagate a particular point of view, the argument that they are a benign curiosity is more difficult to sustain. Where is it likely to end? If the Prince of Wales can exercise covert influence over what sort of building goes up in Chelsea, how can we be sure that he will not at least try to use his royal prestige and connections to impose his will on other decisions which are none of his business?

As a privy councillor I am entitled to give advice to the Queen. If she wants the monarchy to continue on its untroubled way, she should tell her son to respect the restraints of his position. Better still, she should let it be known through the Palace PR machine that she disapproves of his demarche to the Qatari royal family and does not believe that, because they are one feudal monarchy, the Prince of Wales should behave as if he is the heir to another. She might also point out that his reverence for all things ancient does not seem to include respect for the constitution and that republicans like me rejoice at the damage he does to the idea of monarchy.

In a classic piece of doublespeak that would have made George Orwell proud our government has stated that secrecy is required to ensure the impartiality of the head of state.

Gordon Brown has won a few muted accolades for his modest new reform agenda announced in the Commons yesterday. What has attracted less attention was his remark that “there will be protection of Royal Family and Cabinet papers as part of strictly limited exemptions” while informing the Commons of his plans to reduce the 30 year rule to a 20 year rule.

The new restrictions will remove all FOI access to documents relating to the royal family, whereas at the present time they are subject to a public interest test. This is a serious challenge to those, like Republic, who want to hold the monarchy to account and challenge their position in our constitution.

There is absolutely no defence for this reversal of FOI laws. The government clearly agrees, as it has resorted to an extraordinary bit of doublespeak to explain the change. In a statement sent to BBC bloggerMartin Rosenbaum, the Ministry of Justice said:

To ensure the constitutional position and political impartiality of the Monarchy is not undermined, the relevant exemption in the Freedom of Information Act will be made absolute for information relating to communications with the Royal Household that is less than 20 years’ old. After that point – if the relevant Member of the Royal Family is still alive – then the exemption will continue to apply until five years after their death – on an absolute basis for the Sovereign and the Heir to the Throne, and on a qualified basis for other members of the Royal Family.

So the government believes that impartiality and accountability require secrecy. Of course the opposite is true, impartiality needs openness, transparency and scrutiny – it needs to be demonstrated, to be seen to be done, not just promised.

This move clearly has nothing to do with impartiality, it’s to do with protecting the interests of the Windsors. No doubt a lot of royal lobbying has gone on over the past several months to secure this change.

The big question mark is how far will this exemption extend? Will we not be told how Andrew spends his time and our money in his role with UKTI? Will we not be told how many times Charles writes to ministers in an attempt to influence policy? Will there be a block on knowing if Harry and William are abusing their positions to gain favour in the military? Their finances are already opaque as it is, what chances will there be for full disclosure under the new rules?

It all leaves us with one question in mind: what do they have to hide?